In the coal combustion flue gas or the flue gas produced when combusting heavy oil, mercury is contained, in addition to soot, sulfur oxide (SOx), and nitrogen oxide (NOx).
Since the mercury is a toxic substance, mercury content in the flue gas discharged from the stack has been regulated.
For this reason, from the related art, as a method of removing mercury, a technique for blowing powdered activated carbon into the flue gas and recovering mercury by a recovery unit such as a bag filter has been proposed (Patent Literature 1).